Although the enforcement of Minimum Legal Drinking Age legislation has demonstrated effectiveness in preventing sales of alcohol to minors, it is less efficacious in environments (such a private parties) where young adults purchase alcohol legally and allow minors access to it. Alcohol-related crash injury is one of the greatest risks facing underage drinkers, yet there is little research on enforcement models developed specifically to deter underage drinking and driving. However, environmental intervention strategies combining active police enforcement of existing DUI laws (such as the .08 legal limit) with widespread publicity regarding the enforcement have been found to reduce drunk driving. Nationwide zero-tolerance legislation makes it illegal for persons younger than age 21 to drive with any measurable amount of alcohol in their systems. These successful enforcement-and-publicity strategies used to combat drunk driving may be applied to zero-tolerance legislation to deter underage persons from driving with any amount of alcohol in their systems. This application proposes implementing an enforcement-and-publicity zero-tolerance program in two communities in the Mid-Atlantic Region. Both communities are college towns and have a large number of underage drinkers. The zero-tolerance program will be evaluated using a telephone survey of community residents and a web-survey of university students. In addition, roadside surveys will be used to collect physiological measures of blood alcohol concentrations (BACs) from a random sample of young persons recruited in each community on weekend nights. Roadside surveys will allow direct measurement of reductions in underage drinking and driving. Finally, the longevity and sustainability of the program will be examined by measuring the effect of the intervention for 2 years after it ends and by conducting a cost-benefit analysis (should the program prove successful).